Polymers made from 1,4-dioxan-4-one (also known as p-dioxanone) have been employed in the manufacture of absorbable surgical devices. See, for example, U.S. Pat. No. 4,052,988 to Doddi et al. The preparation of the p-dioxanone monomer is described by Doddi et al. as involving the reaction of ethylene glycol, metallic sodium and chloroacetic acid. After several steps including distillation, washing with acetone, addition of hydrochloric acid, precipitation with ethanol, filtration, heating and further distillation, Doddi et al. report that the purity of the crude dioxanone product is about 60-70 percent (See Example 1 of Doddi et al.). Doddi et al. further state that "exceptionally high purity of p-dioxanone monomer is required" to produce strong fibers of polydioxanone. However, although recognizing that high purity is required, Doddi et al. provide no details on how to achieve the required high purity, but rather merely state that the monomer is "finally purified to 99+% by multiple crystallizations and/or distillations" (See Doddi et al. column 4, lines 31-34).
More recent patents directed to polymers made at least impart from p-dioxanone include U.S. Pat. Nos. 4,643,191; 4,646,741; 4,653,497; 4,788,979; 4,838,267; 5,047,048; 5,007,923; 5,076,807; and 5,080,665. However, the steps necessary to achieve purification of the p-dioxanone monomer are not described in detail in these references.
U.S. Pat. No. 3,020,289 to Welpert describes the preparation of 2-p-dioxanone by passing vaporized diethylene glycol through a bed of copper chromite catalyst, with subsequent purification by fractional distillation. The p-dioxanone used in Example 1 of U.S. Pat. No. 3,063,967 to Schultz was twice distilled under nitrogen, presumably for purification. Other patents relating to the polymerization of p-dioxanone include U.S. Pat. No. 3,190,858; 3,391,126; and 3,645,941.